This study investigates individual verb differences in Korean learners‟ use of English non-alternating unaccusatives as well as the factors that influence various errors. Specifically, it focuses on the effects of L1 transfer and animacy of subjects on overpassivization errors. Concordance lines from a learner corpus consisting of 6,572 essays written by Korean college-level learners were analyzed to observe the syntactic distribution across ten non-alternating unaccusative verbs. The results revealed that overpassivization errors show disproportionate dispersion across the ten unaccusative verbs, and that Korean L1 influence is not a significant factor while inanimate subjects influence overpassivization. Furthermore, salient error patterns such as transitivization and overgenerated be were identified from the Korean learners‟ use of unaccusative verbs. This study proposes that some unaccusative verbs are more susceptible to overpassivization errors, and that Korean learners of English will benefit from being able to identify the factors contributing to errors for each unaccusative verb.

The Interface Hypothesis (Sorace, 2011; Sorace & Filiaci, 2006; Sorace & Serratrice, 2009; Tsimpli & Sorace, 2006, among others) states that the grammar external interface is more vulnerable for advanced L2ers or bilinguals than the grammar internal interface, and L1 discourse influence is one factor responsible for their residual difficulty (Sorace, 2005; Sorace, Serratrice, Filiaci & Baldo, 2009). Their study, however, did not disentangle interface effects from L1 influence and it is unclear whether the residual difficulty of advanced L2ers is due to interface effects or L1 influence. The results of the present study which teases the two factors apart show that L1 influence is stronger than interface effects. The results without L1 influence show that the syntax-discourse interface is more vulnerable than the syntax-morphology interface, supporting the Interface Hypothesis. This study examines two sets of data, cross-sectional and longitudinal, on overpassivization of L2 English unaccusative verbs by Chinese and Korean speakers.

Assuming that implicit and explicit knowledge are two different constructs, the current study takes unpaired English unaccusatives as its target grammar feature to investigate these two types of knowledge among Korean EFL learners. In line with the growing body of research utilizing a battery of tests, this study adopts a combination of validated tests to assess implicit and explicit knowledge. In doing so, this study lends support to previous studies, in that the L2 learners’ two types of knowledge are not on par. The findings indicate that proficiency was not correlated with the learners’ explicit knowledge, while it was highly correlated with their implicit knowledge. Moreover, regardless of the grammaticality of the unaccsuative sentences, the role of subject animacy varied depending on the learners’ different type of knowledge in relation to proficiency. Finally, a critical discussion on the importance of separating the two constructs of knowledge and implications for future research are provided.

The present paper addresses Korean EFL learners’ acquisition of psych-verb and unaccusative constructions from a processing point of view. Korean learners’ interlanguage psych-verb constructions and unaccusative constructions are marked by underpassivization and overpassivization, respectively. While both kinds of errors are observed in Korean learners’ data, the processing account of language acquisition predicts that learners will commit underpassivization errors more frequently than overpassivization errors because passivization requires more processing. In order to see if the acquisition of psych-verb and unaccusative constructions is affected by the processing complexity of passivization, the present study compared learners’ performance on psych-verb and unaccusative constructions. Ninety six university students performed a timed grammaticality judgment task on the two types of constructions. The comparison of the learner performances between psych-verb and unaccusative constructions revealed that the learners were more accurate with psych-verb constructions than with unaccusative constructions. The learners’ accuracy with psych-verb constructions increased faster than unaccusative constructions, with the increase of the overall proficiency. The findings suggest that while processibility might be a major issue for low-level learners, there are other factors such as L1 transfer that exert a pervasive influence on the acquisition of psych-verb and unaccusative constructions.